|Events during December
· The Geminids meteor shower is at its height from 12th to 14th December. A predicted average hourly rate of 60 per hour and favourable visibility.
· The winter solstice, when the Sun reaches its most southerly point over the Tropic of Capricorn, is on the 22nd.
· The Moon: Last quarter – 1st and 31st, New – 9th, First quarter – 17th, Full – 24th.
· The Moon has passed through Pleiades each month in 2007, mostly in daylight, and will do so again on the 21st/22nd December during darkness. Binoculars will show more of the stars in the Pleiades cluster.
Snapshot for Christmas Eve
Its worth focusing on Mars again this month before the planet recedes from Earth and diminishes in size throughout 2008.
Mars is at opposition on the 24th December, near its most possible northerly position in the sky. It will be closest to the Earth, at 88.2 million kilometres, on the
18th. On the morning of the Christmas Eve, the full Moon will pass very close above Mars, closest about 5.00h. From the extreme north of Scotland, Orkney and Shetland the
Moon will occult Mars with the planet passing just behind the southern limb of the Moon. A full Moon occulting a planet at opposition is a rare event.
The diagram “Apparition of Mars” shows:
1) The increasing/decreasing apparent diameter from 6 arc-seconds through 15.9 arc-seconds. (A degree is 1/360 of a circle, an arc-minute is 1/60 of a degree and an
arc-second is 1/60 of an arc-minute).
2) The decreasing/increasing distance from Earth in Astronomical Units. (An Astronomical Unit is the approximate mean distance of the Earth from the Sun - just less than
3) The increasing/decreasing northern declination of the planet. (Declination is a measurement of degrees north and south of the celestial equator. An object on the
celestial equator has a declination of 0º, an object above the north pole has a declination of 90º and an object above the south pole has a declination of –90º).
||Mercury is at superior conjunction on the 17th and then becomes an evening object in January 2008.
The best times to observe Mercury are when it is an evening star in the spring and a morning star in the autumn. In midsummer the lighter skies make visibility difficult near the horizon.
||Venus rises at about 6.00h by the 31st and is a brilliant object in the south-eastern sky. The Moon is nearby on the 5th and 6th.
On the 8th June 2004, Venus was at inferior conjunction
and transited the sun. Transits of Venus are rare, taking place at greater
than 100 year intervals and usually in pairs. The last two transits of Venus were in 1874 and 1882. June's transit
began at 7.20h and lasted 6 hours until 13.20h, the total event visible from Europe as a small black disc crossing
the lower part of the Sun from left to right. The next transit will be in late June 2012. After that, transits of Venus
won't occur again until 2117 and 2125.
Before and after inferior conjuction, when Venus is
the closest it comes to the Earth, are the times at which the planet is most brilliant and can be seen setting or rising
4 hours after or before the Sun. The dates of the next two inferior conjunctions are October 28th 2010 and October 26th 2018.
||Mars remains in Gemini, increasing in brilliance to –1.7 magnitude. The planet is at opposition on the 24th with the Moon
closeby on the 23rd/24th.
At opposition on the 28th August 2003, Mars was only 56 million kilometres from the Earth. It showed a
disc of 25.1 seconds of arc across which is almost as large as it can ever appear. Mars started 2003 at 310 million kilometres from
the earth at 4.5 seconds of arc and 1.6 magnitude. By opposition it brightened 50 times to reach -2.9 magnitude but faded to 0
magnitude by December. Even to the naked eye Mars was a striking object in the summer and autumn sky, easily identifiable by its
reddish hue in an area of sky poor in bright stars. Mars will not be as close again for another 15 years.
These favourable oppositions occur every 15 years but other oppositions occur at average intervals of 2 years 2 months. In general Mars is observable every other year, being too close to the sun for favourable conditions during other times. Brightness at opposition varies from -1.0 to -2.9 magnitude, and when furthest from the earth it fades to 1.7 magnitude. The planet can be identified by its orange-red colour.
||Jupiter is in conjunction with the Sun on the 23rd and not observable this month.
Being 770 million kilometres from the sun, the difference in brightness between opposition and conjunction varies less than with Mars, from about -2.8 to -1.8 magnitude.
The 4 largest moons of Jupiter are easily visible through a small telescope, ranging from 4.6 to 5.6 in magnitude. The innermost, Io, takes 1.8 days to orbit the planet making its motion easily detectable within a few minutes.
||Saturn remains in Leo, rising about 22.00h by the 31st. It is stationary on the 20th with the Moon below on the 1st and 29th.
Saturn crossed the equator into the northern hemisphere in 1996 where it will remain until 2010 with the southern side of the ring system facing the earth. Because of its distance, its brightness varies little between opposition and conjunction but is affected by the huge ring system. Seen edge on the rings contribute little or no light.
Every 15 years the plane of Saturn's rings passes through the sun, illuminating first the north and then the south side. For a few days the rings are edge on to the sun. About the same time the earth passes through the ring plane and, depending on the earth's position this may happen just once or 3 times. During 1995/96 there was a triple crossing and the next will be 2038/39. The next single crossings will be in 2009 and 2025.
Saturn's largest moon, Titan, is visible in small telescopes orbiting outside of the ring system.
||Uranus sets about 23.00h by the 31st. The Moon is nearby on the 16th.
Brightness varies slightly reaching 5.6 magnitude at opposition. This is bright enough to see with the naked eye but identifying it against the stars is difficult.
||Neptune sets about 21.00h by the 31st. The Moon is nearby on the 14th.
Neptune has an average magnitude of 7.9 which varies little with changing distance.
||No longer an offical planet and never brighter than 13 magnitude, Pluto is only visible through powerful
telescopes and we therefore do not report on its position in the sky.|
Last quarter: 1st and 31st
New moon: 9th
First quarter: 17th
Full moon: 24th
The Moon in 2007:
The Moon was seen unusually high and low in the sky during 2006 (see Moon). Although the extremities occurred last year, the Moon will still be seen very
high and very low each month this year, most noticeable around full Moon. It will be near full and high around the 2nd and 29th January, the 25th February
and the 24th March; and near full and low around the 1st and 28th June.
During each month of 2007, the Moon will pass through the Pleiades. This will mostly be in daylight but observable 01.00-04.00h 7th August,
0.00-03.00h 28th October and 22.00-01.00h on the 21st to 22nd December. Binoculars will give a clearer view.
|TWILIGHT OBSERVATIONS 2007
Venus - August 22nd to December 31st.
Mars – January 1st to December 24th.
Jupiter – January 1st to June 5th.
Saturn – January 1st to February 10th, and September 9th to December 31st.
Venus – January 1st to August 13th.
Mars – December 24th to December 31st.
Jupiter – June 5th to December 10th.
Saturn – February 10th to August 4th.
Spring equinox 2007 (when the Sun crosses the equator into the northern hemisphere): March 21st at 0.00h GMT.
Autumn equinox 2007 (when the Sun crosses the equator into the southern hemisphere): 23rd September at 10.00h GMT.
Spring equinox 2006: March 20th at 18.00h GMT.
Autumn equinox 2006: 23rd September at 04.00h GMT.
Summer solstice 2007 (when the Sun reaches its most northerly point over the Tropic of Cancer): June 21st at 18.00h GMT.
Winter solstice 2007 (when the Sun reaches its most southerly point over the Tropic of Capricorn): 22nd December at 6.00h GMT.
Summer solstice 2006: June 21st at 12.00h GMT.
Winter solstice 2006: 21st December at 19.00h GMT.
|PERIHELION & APHELION
The Earth is at perihelion (147 million kilometres - its closest to the Sun) on the 3rd January.
The Earth is at aphelion (152 million kilometres – its furthest from the Sun) on the 7th July.
Perihelion: 4th January.
Aphelion: 3rd July.
|SUMMER / WINTER TIME
Spanish and British summer time begins on March 25th 2007.
Spanish and British winter time begins on October 28th 2007.
Note: Spanish summer time is 2 hours ahead of Greenwich Mean Time and British summer time is 1 hour ahead of GMT.
Spanish winter time is 1 hour ahead of GMT and British winter time equals GMT.
Earth moves on its axis with a wobbling motion like a spinning top, the axis tilted away from
the vertical by 23 1/2º. Whereas the axis of a top takes only a few seconds to complete its reeling movement, the period for
Earth is 25,800 years.
This movement causes slow changes in which constellations make up the zodiac. Astronomers use the
real time zodiac, whereas astrologers use the zodiac of 2,000 years ago. After 2,000 years, the first point of Aries is
actually in Pisces. So, for example, when an astrologer says the Sun or a planet is in Aquarius it will physically be
against the background of the preceeding constellation Capricorn.
From left to right (sun to outer solar system), the objects represented are: Sun, Mercury, Venus, Earth, Moon, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.
The added bonus of the clear skies here in Axarquia is that, along with the daily blue sky and sunshine, we have a clear view of the night sky and planets.
With the aid of a simple pair of binoculars, there are wonderful close-ups of the moon. Whilst, through a modest telescope, we are able to see the moons of Jupiter, the rings around Saturn, the phases of Venus and transits of Venus and Mercury. I am constantly amazed when friends, of all nationalities, who visit at night declare that they have never had the opportunity to look at the sky in detail before.
For newcomers to planet spotting, a good hint is that the planets always travel within a few degrees of the path of the sun.
The path that the sun appears to travel against the star background is called the ecliptic. It marks the centre of the band of sky within which the moon and planets are
found. This area is known as the zodiac. The ecliptic passes through the 13 zodiacal constellations of Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio,
Ophiuchus, Sagittarius, Capricorn and Aquarius. Ophiuchus does not appear in the astrologer's zodiac although the planets spend more time in it than in Scorpio. Astrologers
use a different zodiac from astronomers for reasons explained in the notes on precession.
Above we note the planets and some of the other objects that can be seen by the naked eye during the current
month and year. Unless otherwise stated, time references are local Spanish time.